Welburn Julie P I, Tucker Julie A, Johnson Tim, Lindert Lisa, Morgan Marc, Willis Antony, Noble Martin E M, Endicott Jane A
AstraZeneca Pharmaceuticals, Alderley Park, Macclesfield, Cheshire SK10 4TF, United Kingdom.
J Biol Chem. 2007 Feb 2;282(5):3173-81. doi: 10.1074/jbc.M609151200. Epub 2006 Nov 9.
Inhibition of cyclin-dependent kinase 1 (CDK1) activity by Tyr-15 phosphorylation directly regulates entry into mitosis and is an important element in the control of the unperturbed cell cycle. Active site phosphorylation of other members of the CDK family that regulate cell cycle progression instates checkpoints that are fundamental to eukaryotic cell cycle regulation. Kinetic and crystallographic analyses of CDK2-cyclin A complexes reveal that this inhibitory mechanism operates through steric blockade of peptide substrate binding and through the creation of an environment that favors a non-productive conformation of the terminal group of ATP. By contrast, tyrosine phosphorylation of CDK2 alters neither its Km for ATP nor its significant intrinsic ATPase activity. Tyr-15-phosphorylated CDK2 retains trace protein phosphorylation activity that should be considered in quantitative and qualitative cell cycle models.
酪氨酸-15磷酸化对细胞周期蛋白依赖性激酶1（CDK1）活性的抑制直接调控有丝分裂的进入，并且是未受干扰的细胞周期控制中的一个重要因素。调节细胞周期进程的CDK家族其他成员的活性位点磷酸化建立了对真核细胞周期调控至关重要的检查点。对CDK2-细胞周期蛋白A复合物的动力学和晶体学分析表明，这种抑制机制通过肽底物结合的空间位阻以及通过创造有利于ATP末端基团非生产性构象的环境来发挥作用。相比之下，CDK2的酪氨酸磷酸化既不改变其对ATP的米氏常数，也不改变其显著的内在ATP酶活性。酪氨酸-15磷酸化的CDK2保留微量蛋白磷酸化活性，这在定量和定性细胞周期模型中应予以考虑。
